approach to hyponatremia, causes, investigation, pathophysiology, management

approach to hyponatremia, causes, investigation, pathophysiology, management

1. Approach to Hyponatremia CME Guide: Dr. B. D. Jha Dr. Praveen Kumar Giri Dr . Sahana Tamrakar Presented by: Gaurav Thakuri MBBS (NEPALESE ARMY INSTITUTE OF HEALTH SCIENCES)

2. Serum sodium level Hyponatremia Normal Hypernatremia <135meq/L 135-145meq/L >145meq/L Mild hyponatremia 130 to 134 meq /L Moderate hyponatremia 120 to 129 meq /L Severe hyponatremia Less than 120 meq /L

3. HYPOVOLEMIC EUVOLEMIC HYPERVOLEMIC ANY CAUSE OF VOLUME DEPLETION GI CAUSE RENAL CAUSE SIADH RESET OSMOSTAT CIRRHOSIS NEPHROTIC SYNDROME CARDIAC FAILURE VOMITING DIARRHEA PANCREATITIS DIURETICS EXCESS MINERALO CORTICOID DEFICIENCY CEREBRAL SALT WASTING

4. DIAGNOSTIC EVALUATION Step 1: Consider wether plasma osmolarity normal or elevated?? Serum osmolarity =2 x [Na ]+[ glucose mg / dL] /18 +[ BUN mg / dL] / 2.8.

5. Suppose a diabetic patient presents to the hospital with vomiting and diarrhea and is found to also be in DKA If his serum Na 118 meq /L and serum glucose 500mg/ dL , does the hyperglycemia completely explain the hyponatremia ???

6. Step 2: check Urine osmolarity Hypotonic Hyponatremia Urine osmolartiy < 100 mosm /kg Urine osmolarity > 100 mosm /kg Primary polydipsia Beer potomania Reset osmostat Go to step 3

7. Step 3: assess volume status and measure U Na Urine sodium Una < 20 meq /L Una >20 meq /L Volume status Hypovolemia Dehydration from GI lossess Insensible losses Dehydration from diuretics Mineralocorticoid deficiency Euvolemic Primary polydipsisa SIADH Hypothyroidism Hypervolemia CHF Cirrhosis Advanced renal disease

8. Step 4: consider additional tests Additional lab findings Suggested diagnoses Sr. uric acid < 4mg/ dL And/ OR BUN <5mg/ dL SIADH Metabolic alkalosis + hypokalemia Volume depletion from vomiting or diuretics Metabolic acidosis + hypokalemia Volume depletion from diarrhoea Metabolic acidosis + hyperkalemia Primary adrenal insufficiency

9. Step 5: If SIADH is considered Review medication list Smoking history Chest X ray Detailed neurological examination Consider head CT

10. Management Rate of sodium correction Rate of sodium correction 6 to 8 mEq /L in 24 hours But if symptomatic achieve this in 6 h or less i.e rate of 1 -2 mEq /L untill seizure subsides.

11. Calculation of sodium deficit • Sodium deficit = total body water (TBW) × (desired serum Na − measured serum Na). • TBW = body weight (kg) × Y. Y= Children Adult men Adult women Elderly men Elderly women 0.6 0.6 0.5 0.5 0.45

12. For example, in a 60-kg woman with a serum sodium of 115 mEq /L with a goal of increasing sodium by 8 mEq /L in first 24 h, Sodium deficit = ( 60X0.5)X(123-115 ) = 240 mEq.

13. When to use 3% NS and when 0.9%NS?? Most manifestations are neurologic Fatigue at 125-130 in Head ache acute and 120-125 in ch. Nausea/ vomiting Confusion at 120 to 125 in acute and Seizure 110 to 120 in chronic Coma

14. 3% NS shoul d be reserved only for severe neurologic symptoms 0.9% NS should be used in patient with hypovolemia and mild to moderate hyponatremia

15. If SIADH Additional Fluid restriction in mild to moderate cases But if cause is SAH fluid rest is contraindicated Oral salt tab Vaptans : conivaptan

16. If hyervolemic hyponatremia Fluid rest Loop diuretics Albumin supplement

17. •Harrison's Principles of Internal Medicine, 18th edition, Anthony S.Fauci , MD, Eugene Braunwald , MD, Dennis L. Kasper, MD, Stephen L. Standard treatment protocol of emergency health service package 2078 A step-wise approach vol II second edition Guyton and hall textbook of medical physiology 13 th edition http://www.youtube.com/@ StrongMed All images are copyright to their respective owners. All product names, logos and brands used are properties of their respective owners.